Unless I'm seriously misreading your code, you have all arguments of compat syscall sign-extended by asm glue. If that's the case, consider what will happen to 32bit binary doing llseek(fd, 0, 0xffffffff, &pos, SEEK_CUR) on 32bit and 64bit hosts resp. The former will move the current position by 4Gb forward; the latter - by one byte backwards... sys_llseek() will do the right thing for compat on architectures that zero-extend the arguments of compat syscall; x86/sparc/ppc/arm64 fall into that category. mips and (AFAICS) tile do not (and s390 is just plain weird and needs wrappers for just about everything). mips has sys_32_llseek() for a good reason; we probably want to take that into fs/read_write.c, but on such architectures something *is* needed - plain sys_llseek() won't work... FWIW, I suspect that we want __ARCH_COMPAT_ZERO_EXTENDS or __ARCH_COMPAT_SIGN_EXTENDS defined in asm/compat.h; the need of sys_llseek() would be "it's 32bit or it has compat and it's zero-extending", while "has compat and it's not zero-extending" would pick compat_sys_llseek() instead. __ARCH_WANT_SYS_LLSEEK shouldn't exist... And things like "do we need compat_sys_lseek(), compat_sys_truncate() and their ilk" could be expressed via those as well - compat && !sign_extends. Comments? -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
